US2059557A - Copper-base alloys - Google Patents

Description

base alloys and this application contains subject matter in common with my application, Serial No. 696,918 filed November 6, 1933.

- about 3%tin. For instance, in order to form wire fusion, break the ingot down cold, anneal it, roll it melting point than the bronze. elements are the first constituents to crystallize I out/of the molten mass on cooling and thus efing about 3% to about 10% tin by the addition of effectiveamounts of one or both of the elements 55 chic umand vanadium and the further addition phorus and up to 3% nickel, the latter produc- 55 influence the atoms of copper and tin to crystal;

'" ing thehot workability of the bronze. J

Patented Nov. 3,1936

UNITED ls TA'lES PATE om v Michael George Carson, New York, N. Y., as'signor to Union Carbide and Carbon Research Laboratories, Inc., a corporation of New York No Drawing. Application March 1'7, 1936, Serial No. 69,361

3 Claims. (01. 751-154 The present invention relates to the coppr-- of substantial amounts of iron or cobalt. II desired, the chromium or vanadium, or both, may be added in the form of ferro alloys, for instance,

, a commercial low carbon ferrochromium contain- Copper-tin alloys, sometimes containing other ing about 50% to 95% chromium, or a low carbon 5 elements such as phosphorus, zinc, manganese, ferrovanadium containingv about 30% to 90% and nickel, are well-known to the art and are :vanad.ium, or a ferroalloy containing both vana-- formed into various shapes by casting and by" diumand chromium. various known processes for working metals in When both iron andchromium or vanadium are added, the iron crystallizes chiefly with the chromium .or vanadium so that a tin bronze containing say'2% of 50% ferrochromium appears, or sheets fromthe so-called phosphor bronze, it under the microscope, more like an alloy containhasbeen necessary first-to heat the cast ingot to ing 1.75% to 2%, chromium than like one contain a high temperature of notless than 700 0., hold ing 1% of chromium as would have been the case it at this high temperature for many hours for had the irongone into'solid solution in the alpha the purpose of homogenizing the ingot by dif-' tin bronze.

I Tin bronzes made according to the present invention and containing 3% to 10% tln,-0.5% to to repeat the alternate cold working and anneal- 2% chromium or 0.2% to 1% vanadium and up ing steps until the metal .has attained the det about 2% iron. may be taken from the ingot sired S ea d s pet 0 St has hot Wo mold as soon as they are sufliciently cold to handle. been cause the metal cannot withstand reheated to 700 to'800" C., forged to about onet pplication of a forging hammer or hot ro l half of the area of the original cross-section, and. without cracking and breaking to pieces. finished into the desired shape'by hot rolling.

I ave discovered h pp alloys can be Vanadium is somewhat diificult tointroduce made forgeable and rollable at elevated temperad i ad it quite expensive, for h h tures by introducing into the alloys certain addisons the use of an'amount exceeding that which tional elementswhich are only li h ly s l in is necessary for the development of the capacity the cold state. However, it has heretofore been diflicult to hot work tin bronzes containing above down cold to a certain extent, again anneal it, and

the c y of solid pp r nd of id lp in for hot work (about 1%) is not usually de irable. a0

bronze, and which in addition have a much higher The situation in the case of chromium is different Such additional it can be introduced into molten bronze easilyenough, and itsexcess above the really necessary amount of 1.5% does not seriously affect hot workability but develops interesting and industrially desirable antifriction characteristics. lize in-a more o sta proportion th is It is well known, for instance, that the' usual case with normal binary t n bro a With bearing bronzes, working without a lining of alow terna y i bronzes in which the third element melting antifriction alloy and containing tin in forms a component of the. alpha solid solution. amount-S, sufficient tdproduce, second Suitable additional elements are chlfomium and stituent the delta eutectoid or bronzite, do not vanadium and, to a lesser degree, iron and cobalt. work wen if the bearing happens to become over; Vanadium is the most eifective of these elements heated. In fact, the bearings of hot rolling mills but it is diflicult and expensiveto introduce into a used in steel making cannot b made at all molten copper or molten bronzes. For this-reasuch an l l plex (alpha plus ,delta) bronzes. The son chromium is preferred, this element being eflatter fail rapidly n their temperature apfect favorable distribution of crystal nucleiv and fective as soon as abort 0.52%, is addeldiq Ivflirog g: preaches 500 C cobaltalonewere o euse ,a eas- 0 on v v To copewith this handicap special bronzes have necessary to produce the desired effect of improv been intrpduced containing l /ma t nd According to the present invention hot work-' thelfefole. i n0 ta P In P ce Of ability is imparted to copper tin alloys containthe delta pha a hard Constituent. qui Stab at high temperatures, is introduced into the structure of such bronzes by adding up to 0.3% of phos ing to some extent at least, flne grains of nickel phosphide of the supposed formula NisP.

I have found, however, that by increasing the amount of chromium added to the copper-tin base bronze, the phosphide can be replaced by a far larger and far more efficient amount of chromium which crystallizes in the shape of irregular single crystals or their star-like aggregates. While the actual hardness of these chromium crystals is not well known, it can be safely assumed to be in the neighborhood of 200 Brinell, while the hardness of nickel-phosphide, a definite intermetallic compound, must be considerably higher. Therefore, the probability of scratching the journals of the rolling mill is far less in the case of a chromium containing bronze.

The amount of chromium present in such a tin bronze may be as high as 10%, but not more than 4 or 5% is desirable. Likewise, the amount of iron or cobalt may be as high as 10%.

The method of making such chromium or vanadium containing bronzes may vary to a great extent, as to raw materials, type of furnace, material of the crucible, etc. The only essential thing is that the metal should be properly deoxidized before the introduction of the chromium and protected from further oxidation by a layer of a liquid flux. For the latter I prefer a mixture of fluorides of sodium and calcium, to which other fluorides may be added. I may employ a flux of commercially pure fused boric acid and borax and its mixtures with glass also maybe used, but with less convenience.

To illustrate a way of preparing such alloys, I shall state the following:

I take commercial bronze ingots and melt them in the usual graphite-clay crucibles. I add to them enough copper to bring the content of tin down to the desired level. I cover the molten alloy with a layer of fluorides about one-eighth inch in thickness. in the molten state. I add just enough phosphor copper to make the melt quite fluid, usually not more than 0.05% phosphorus. Then I add chromium metal orferrochrome or ferrovanadium or ferrochrome-vanadium in pieces large enough to be produced conveniently and without much expense and small enough to allow them to be fully covered by the liquid fluoride in those parts which protrude above the level of the molten bronze due to the difference in the specific weights.

Next, I raise the temperature in the metal either by feeding more fuel and air to the furnace, or increasing its current input until it comes to about 1250 C. At this point chromium dissolves rapidly as does ferrovanadium. From time to time the pieces of the metal or of the ferro-alloy are pushed down under the surface of the molten bronze and the latter stirred to check the supersaturation of the top-layers with dissolved chromium or vanadium.

The liquid flux is next removed, by adding dry sand to it. In this manner a pastymass of fluoride soaked sand forms, and it can be easily kept from flowing down into the mold.

The final casting proceeds as usual, whether it is the manufacture of sand castings, ingots for forging, or castings 'in permanent molds. In the latter case about 0.2% aluminum may be added to inhibit the welding of the molten metal to the metal of the permanent mold.

It is to be understood that the copper-base alloys of the present invention may contain, in addition to tin and one or more of the elements chromium, vanadium, and iron in proportions within the limits specified herein, one or more of the elements, nickel, manganese, and aluminum.

in proportions up to say 10%. These elements do not contribute to the workability of the alloy in the hot state, but may be added for their known improvement efiects in other respects. Small amounts of the usual deoxidizers, such as phosphorus, magnesium, and the like may also be present.

I claim:

1. A hot workable copper-base alloy containing about 3% to 10% tin, about 0.2% to 10% of mixtures of chromium and vanadium, which impart hot workability to the alloy, and the remainder substantially all copper.

2. A hot workable alloy containing about 5% to 10% tin, about 3% to 5% of mixtures of chromium and vanadium, and the remainder substantially all copper.

3. A hot workable alloy containing about 5% to 8% tin, about 0.5% to 1.5% of mixtures of chromium and vanadium, and the remainder substantially all copper.

MICHAEL GEORGE CORSON.